App life milage and max speed is wrong

My app on my iPhone is screwy. I used to have a max speed of 25.6 km/h and a life km of 60.

The max speed has now dropped to 21 and the life km is now 19. I'll turn the board off and the return to the app and it will flash to the larger number of 60 km for the life but only for a second or two as it then settles on the 19.